Today, traction converter circuits are employed in a multitude of power electronic applications, more preferably for rail-bound vehicles such as electric railways. Especially during country-overlapping use of rail-bound vehicles it must be possible for the drive energy to be drawn or fed from different electric supply networks, i.e. from different electric DC voltage networks and AC voltage networks of different network voltage. This requires traction converter circuits which can be coupled to an electric supply network based on a DC voltage and also to an electric supply network based on an AC voltage. Popular electric supply networks, more preferably for rail networks with an alternating voltage source are based on an alternating voltage of 15 kV with a frequency of 16⅔ Hz or of 25 kV and 50 Hz. Popular electric supply networks, more preferably for rail networks, with a DC voltage source are based on a DC voltage of 1.5 kV or 3 kV. A suitable traction converter circuit for coupling to an electric DC voltage network is stated for example in DE 1 479 558 A1. Therein, the traction converter circuit comprises a network converter, which network converter on the DC voltage side is connected with a DC voltage circuit, wherein the DC voltage circuit can be switched to the electric DC voltage network. In addition, the traction converter circuit has a transformer with a primary winding and a secondary winding, wherein the network converter on the alternating voltage side is connected with the primary winding of the transformer. Furthermore, a converter unit is provided, which converter unit on the alternating voltage side is connected with the secondary winding of the transformer. According to the method the network converter is controlled by means of a predeterminable network converter control signal for the setting of the network converter alternating voltage, wherein the network converter control signal is typically generated through pulse width modulation of a sinusoidal signal, popularly a sinusoidal voltage signal with a triangular signal, as a result of which a switching frequency in the kilohertz range is popularly obtained.
At its alternating voltage side the network converter generates a voltage with a basic frequency for example of 100 Hz. As a consequence, a double frequency power oscillation of then 200 Hz is obtained which must not be passed on to the DC voltage side in the DC voltage circuit and consequently into the electric DC voltage network. To this end a filter circuit (acceptor circuit) in form of an LC filter must be provided on the DC voltage circuit which is mainly tuned to double the basic frequency of the voltage on the alternating voltage side of the network converter so that this double frequency voltage component can be filtered out on the DC voltage side of the network converter. However, such a filter circuit on the DC voltage side is very heavy, requires a lot of space, is lossy, reduces the reliability of the traction converter circuit and significantly increases the hardware costs.